Falkland Is SG115 2 1/2d on 2d on Cover to NORWAY RARE RPS Cert

19th Feb Cover from South Georgia to Trondheim in Norway. The only other example I can find was a Front in the Stanley Collection (Spink March 1998 lot 590) and sold for 2300 pounds. This front was used on the same date as this Cover (19th Feb 1928) This stamp is Very Rare Postally used on cover. My copy of Heijtz (2006) price it at 6000 pounds (four times a philatelic cover).